Sending items to a variety of locations around the world typically includes several sorting steps in which items are sorted according to their final destination. Often, these items are sorted one or more times at each of a variety of different sort locations, each sorting step being designed to move the item closer to its final delivery destination. For example, an item may be initially received by a carrier and sorted into one of several groups bound for one of several intermediate sorting hub facilities. The sorted items may be placed on feeder trucks, rail cars, airplanes, or other transportation vehicles and taken to intermediate sort hub facilities, where the group of items may be again sorted into various groups bound for a second sort location. This process may continue until the items are sorted into groups bound for a common final delivery vehicle and then taken to their final delivery destinations.
Modern sorting systems may use a complex system of conveyors, slides, bins, and other devices to sort items according to one or more characteristics of the item. The characteristics used to sort items may be indicated on the item using indicia, such as printed text, symbols, or pictures designating, for example, a final delivery address. Alternatively, sort characteristics may be identified using other means, such as electronic tags readable using electronic readers or scanners.
Although item sorting has been greatly improved through the use of modern technologies such as the mentioned electronic readers and computer-controlled conveyor systems, the sorting process still requires a knowledgeable and attentive labor force to coordinate and track the items during sorting. The sorting environment may be described as dynamic and busy, where personnel experience a constant barrage of various stimuli requiring quick decision-making and physical activity. The sorting personnel may be required to determine an appropriate sorting location for each item that enters the work area and quickly move the item to the appropriate location.
In many existing systems, each intermediate sort step may require separate handling instructions to be printed on a label applied to each item. However, for items requiring multiple intermediate sort steps, continued re-labeling creates a significant cost and adds an additional risk of potential errors in the already complex sorting process.
As illustrated by U.S. Pat. No. 7,090,134, incorporated in its entirety herein, the carrier industry has made previous efforts to reduce the costs and risks of error involved in the intermediate sort steps by projecting sort instructions directly onto items moving along a conveyor belt. However, there exists a continuing need for alternative means for providing clear instructions to item sorting personnel working in a variety of environments each having a different configuration.